Satellite propulsion and power system

Abstract

In the preferred embodiment of the invention, a cooled bipropellant thruster 70 for controlling the on-orbit position and orientation of a spacecraft is provided. The cooled bipropellant thruster 70 uses a liquid fuel and liquid oxidizer. The liquid fuel is decomposed in a first chamber 72 with a catalytic bed of decomposition material 74 and produces at least one reaction gas, which flows to the second reaction chamber 90. The second reaction chamber 90 is heated by the reaction gas, but is cooled by liquid oxidizer flowing through cooling passages 92, 94, 98, and 102, which brings the oxidizer into a heat exchange relationship with the second reaction chamber 90. During the heat exchange relationship, heat is transferred from the second reaction chamber 90 to the oxidizer and the oxidizer transforms into a gas. The gaseous oxidizer is fed into a second reaction chamber 90 to secondarily react with the reaction gas.

What is claimed is: 
     
       1. A thruster for station keeping and attitude control of a spacecraft which also has an apogee engine which is used for the apogee kick phase of a mission, said thruster comprising: a first tank of a non-cryogenic fuel consisting of essentially pure hydrazine which is in a liquid state at ambient temperature;   a second tank containing a non-cryogenic oxidizer which is in a liquid state at ambient temperature, said oxidizer being nitrogen tetroxide;   said hydrazine tank and oxidizer tank supplying fuel to the apogee engine during the apogee kick phase of the mission of the spacecraft;   said station keeping and attitude control thruster being fed by the same hydrazine and oxidizer tanks during station keeping and attitude control phases of the mission of the spacecraft, said thruster including:   a first body defining a first reaction chamber having therein a catalytic bed of decomposition material;   a second body having an inner surface defining a second reaction chamber;   means for feeding the liquid hydrazine from the tank thereof to the first reaction chamber to react exothermically with the catalytic bed of decomposition material and produce a first group of reaction gases, the reaction gases flowing from the first reaction chamber into the second reaction chamber and heating the second body;   at least one passageway formed in the second body, said passageway having an inlet and an outlet, said inlet being coupled to receive the non-cryogenic oxidizer while in a liquid state from the oxidizer tank, with the liquid oxidizer flowing through a first portion of the passageway to receive sufficient heat from the second body to initially transform a fraction of the non-cryogenic liquid oxidizer to a heated gas phase, said oxidizer continuing to flow through other passageway portions to receive sufficient heat from the second body to substantially completely transform the oxidizer to a gas phase, the phase change of the oxidizer from liquid to gas serving to cool the thruster during low thrust burns for station keeping and attitude control maneuvers of the spacecraft; and   means for feeding the gaseous oxidizer from the outlet of the passageway into the second reaction chamber to react as a gas with the reaction gases flowing from the first chamber to provide sufficient energy to perform station keeping and attitude control of the spacecraft.   
     
     
       2. The thruster of claim 1 wherein the liquid oxidizer flows in the passageway sufficiently to transform the oxidizer into a superheated gas at a temperature of about 250°-300° F. 
     
     
       3. The thruster of claim 1 which further comprises: flow swirler means in the passageways for swirling the oxidizer to promote heat transfer and removal of the oxidizer from the passageway.   
     
     
       4. The thruster of claim 1 which further comprises: a plurality of elongated substantially parallel conduits in the second body and connected together at ends thereof to form a serpentine flow channel for the oxidizer which progresses radially inwardly from said inlet to said outlet; and   injectors connected to said outlet for injecting the oxider gas into the second reaction chamber.   
     
     
       5. The thruster of claim 1 wherein the injectors serve to inject the oxidizer gas at converging radially inward angles into the second reaction chamber.